Field
The present invention relates to a cutting apparatus of a cutting system using a robot, and more particularly, a cutting apparatus of a cutting system using a robot which prevents chattering of the shaft and minimizes the diameter of a sleeve while increasing the rigidity against bending of the sleeve, thereby being capable of reducing the damage and interference of a bone, a muscle and surrounding soft tissue during surgery, and improving the durability.
Description of the Related Art
Generally, in case the joint disease is in the early stage or is slight, the disease can be treated with non-surgical treatment such as a medicine treatment and a physical treatment. However, in case the joint disease is severe or it is impossible to live on a daily routine, it should be treated with a surgical treatment.
The surgical treatment may comprise arthroendoscopic surgical operation, autologous chondrocyte implantation, etc., and in case of a severe disease, an artificial joint surgery is performed. The artificial joint surgery is representatively performed by a human and a robot.
The artificial joint surgery using a robot is the surgical procedure of cutting knee bone and implanting the artificial knee joint (implant a of FIG. 1B) by rotating a cutter of a cutting apparatus provided in an end part of the flexible arm of the robot according to the information input into a computer.
FIG. 1A is a drawing of a conventional cutting apparatus of a joint cutting system using a robot, and FIG. 1B is a schematic perspective view of an embodiment of an artificial joint (implant) operated on the knee joint. As shown in FIG. 1 and FIG. 2, the conventional cutting apparatus comprises a head 110 having a diameter of 7.8 mm and a shaft 120 having a diameter of 2.3 mm. The head 110 is installed on the end portion of the flexible arm of the robot and is equipped with a cutting blade at outer portion and front end portion of the head 110. The rear end portion of the shaft 120 is coupled with a motor M installed on the front portion of the flexible arm of the robot.
And the outer portion of the shaft 120 is supported by a sleeve 130 fixed to a housing of the motor M in order to be rotatable. Therefore, when the shaft 120 rotates, chattering or bending of the shaft 120 are not generated. Also, the head 110 protruded over the sleeve 130 performs cutting of bone while rotating.
The shaft 120 of the cutting apparatus shown in FIG. 1 as described above is inserted into a long sleeve 130 and then rotates. Therefore, since severe friction is generated, there are limitations that in use of long time the abrasion of the shaft 120 may occur and the shaft 120 may not rotate smoothly.
FIG. 2 is a drawing of another embodiment of a conventional cutting apparatus of a joint cutting system using a robot, and shows the cutting system using a robot disclosed in Korean Patent Registration No. 10-0873014.
Referring to FIG. 2, the joint cutting system using the robot includes a flexible arm and a motor M provided on the front end portion of the arm, wherein the sleeve 14 is coupled to the housing of the motor and the cutter 10 coupled to the axis of the motor is rotatably coupled into the sleeve 14. The cutter 10 has a round-bar shape and is coupled in order to rotate within the sleeve 14 by the motor. And the system includes the shaft 11 having cantilever shape of being extended outside the sleeve 14, and the head 12 provided on the front end portion of the shaft extended outside the sleeve 14. The head 12 enters inside the bone like entering inside a tunnel while cutting the bone. For doing this, the length of the cantilever of the shaft 11 and the diameter of the head may be respectively 20˜30 mm and 1.5˜4.0 mm, or 70˜80 mm and 4.0˜6.0 mm.
Because the cutting apparatus shown in FIG. 2 as described above operates on the knee joint with tunnel-like cutting techniques using the cutter of cantilever shape with the minimum diameter and the maximum length optimized according to the diameter, the bone can be cut quickly and safely, and the damage of muscles or surrounding soft tissue attached to the bone can be reduced to some extent. However, there are disadvantages that because the shaft 11 is not supported by the sleeve 14 so as to be exposed as cantilever shape, bending and chattering of the shaft 11 are generated. In particular, considering that upon operating, the shaft 11 rotates at a speed of more than 60,000 rpm, there is disadvantage of lowering the safety, for example, a risk of breakdown of the shaft 11. In addition, considering the chattering of the shaft 11, there is limitation of the length of being exposed as the shape of the cantilever. Therefore, there is problem that the shaft 11 cannot be used at all in case the operative position is deep.
Recently, in order to compensate the disadvantages of FIGS. 1A and 2 as described above, the damage and interference of the bone, the muscle and the surrounding soft tissue was minimized by reducing the diameter of the sleeve. In addition, the cutter support member equipped with a plurality of bearings within the sleeve has been developed. (not shown)
However, in this type of cutter support member, bearings have to be inserted inside the sleeve of pipe-shape, and because the diameter of the sleeve must increase in order to meet the rigidity against bending, there is disadvantage that the overall outer diameter increases excessively. This increase of outer diameter of the sleeve causes the damage and the interference of a bone, a muscle and the surrounding soft tissue during operation.